Figure 1.

Alignment of Stt4p and Pik1p. The STT4 gene encodes a high-molecular-weight protein possessing three conserved domains in its carboxyl terminus. Only the catalytic kinase domains of Stt4p and Pik1p share similarity, whereas the lipid kinase–unique domains of each protein diverge extensively. Additionally, Stt4p appears to contain a pleckstrin homology domain, whereas Pik1p does not. Neither protein contains obvious transmembrane domains. Oligonucleotides for PCR mutagenesis of STT4 are shown. Scale bar, 100 amino acids.